Disclosed techniques relate to an acceleration data structure for ray intersection with a many-to-many mapping between bounding regions and primitives. In some embodiments, one or more graphics processors access data for multiple graphics primitives in a graphics scene and generate a spatially organized data structure. Some nodes of the data structure indicate graphics primitives and some nodes indicate coordinates of bounding regions in the graphics scene. In some embodiments, the spatially organized data structure includes a node with a bounding region for which multiple primitives are indicated as children and also includes a primitive for which multiple bounding regions are indicated as parents. Disclosed techniques may generate bounding regions that closely fit primitives, which may reduce primitive testing for ray tracing. This in turn may increase performance or reduce power consumption relative to traditional techniques.